JPS5966324A - Gas sorbing cylinder - Google Patents

Abstract

PURPOSE:To simply and accurately predict the breakdown of a sorbent agent to accurately estimate an effective operation time and to obtain a sorbing tower unnecessary for taking a large safety factor, by interposing a detecting agent layer between sorbent layers. CONSTITUTION:Dried activated alumina is impregnated with a solution mixture consisting of phenolphthalein, an aqueous potassium hydroxide solution and methanol and the impregnated alumina is dried by heating under vacuum to obtain a detecting agent. A transparent cylindrical container 1 is successively filled with a sorbent agent, the detecting agent and the sorbent agent in this order from the upper part thereof to form a sorbent cylinder 5 having the first sorbent layer 2 with a height of 45cm, the detecting agent layer 3 with a height of 5cm and the second sorgent layer 4 with a height of 5cm. A silicon wafer etching tank 6 containing an etching liquid consisting of hydrochloric acid, acetic acid and phosphoric acid stored therein is connected to the upper end of the gas sorbent cylinder 5 by a pipe 7 while a vacuum pump 8 is connected to the lower end of said gas sorbent cylinder 5 by a pipe 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas sorption cylinder for removing a specific component in a gas mixture by means of a sorbent, and more particularly to a gas sorption cylinder for predicting breakthrough of the sorbent. related to.

Conventionally, acidic, basic, oxidizing and/or reducing gases (including mist) used and/or generated in various plants and factories have been used to rust the metal parts of machinery and buildings. It is considered a harmful gas because it harms humans, animals such as livestock, and plants such as crops and pollutes the environment, and harmful gases or harmful gases in gas mixtures are not emitted from plants and factories. That is what is needed.

These harmful gases are usually sorbed (absorbed and/or
or adsorption (the same applies hereafter).

Sorption devices for this purpose include those made by molding the absorption agent into granules, or those made by impregnating a carrier such as granular activated carbon, silica, or alumina with an agent suitable for sorption and removal of the target harmful gas. One typical example is a sorption tube filled with a tubular container.

Such sorption cylinders are designed according to the conditions under which they are normally used.
However, during actual operation, the total gas flow rate, harmful gas concentration, type, etc. often change, so it is difficult to predict the effective operating time, and it is difficult to predict the effective operating time. It has the disadvantage that it is often an economical device.

In order to overcome these drawbacks, there is a sorption tube in which a detection agent for detecting the breakthrough of the sorbent is filled as a mixture with the sorbent or in contact with the lower end of the sorbent layer. However, when the detection agent changes color, such a sorption cylinder
A large amount of harmful gas has already been discharged from the outlet of the sorption cylinder, so it is difficult to completely eliminate the above-mentioned drawbacks.

The present inventors have conducted extensive research in order to eliminate the drawbacks of conventional sorption tubes, and as a result they have arrived at the present invention.

That is, an object of the present invention is to provide a sorption tube that can easily and accurately predict the breakthrough of a sorbent, thereby accurately predicting the effective operating time, and which does not require a large safety factor. be.

Therefore, the present invention provides a gas sorption cylinder filled with a sorbent for sorbing and removing a specific component in a gas mixture and a detection agent for detecting breakthrough. This is a gas sorption cylinder characterized by having a detection agent interposed therebetween.

There are no particular restrictions on the specific component in the gas mixture that is removed by the sorption cylinder of the present invention, but it is usually a harmful gas (including mist, hereinafter the same). Typical examples of harmful gases include vapors generated from mineral acids such as nitric acid, hydrochloric acid, sulfuric acid, and hydrofluoric acid, vapors of organic acids such as formic acid, acetic acid, and propionic acid, and/or acidic gases such as the mist of these acids. ,
Basic gases such as vapors and/or mists of ammonia, methylamines and ethylamines, oxidizing gases such as chlorine, bromine and ozone, and hydrides such as phosphine, arsine, silane, diporane, trimethylaluminum, triethylaluminum, triethyl These include reducing gases such as vapors of organometallic compounds such as indium, dimethylzinc, and trimethylgallium.

As the sorbent used in the present invention, sorbents known per se can be used, but typical examples commonly used include oxides of alkali metals and alkaline earth metals for acidic gases. and granulated solid basic compounds such as hydroxides, and these basic compounds as carriers for catalysts, such as activated carbon, silica, alumina, clays, and synthetic zeolites. There are also products in which the carrier is impregnated with or adhered to a material that is also used in the carrier.

For basic gases, for example, carriers as described above are impregnated and supported with non-volatile mineral acids such as sulfuric acid and phosphoric acid, heteropolyacids such as phosphomolybdic acid and silicotungstic acid, and carriers such as alumina are used. There are granular solid acids such as

Examples of reducing gases include oxidizing substances such as a mixture of potassium dichromate and sulfuric acid, and carriers impregnated with such oxidizing substances and supported thereon.

Further, for oxidizing gases, there are reducing substances such as ferrous sulfate, and those in which such reducing substances are supported on the above-mentioned carriers.

There is no particular restriction on the amount of the sorption agent supported on the carrier, but it is usually preferably 3 to 100 parts by weight per 100 parts by weight of the carrier.

As the detection agent, there may be used various known indicators alone or together with an indicator and a sorption agent supported on a carrier as described above, with the latter being preferred. In the latter case, the amount of sorbent supported only needs to be lower than the amount of sorbent supported in the sorbent layer on the inlet side, and in practice, it is usually one of the amount of sorbent supported in the sorbent layer. /2 or less, preferably 1/5 or less.

There is no particular limit to the amount of indicator, but usually carrier 1
0.001 to 1 part by weight, preferably 0.05 to 0.5 part by weight.

There are no particular restrictions on indicators, but so-called neutralization titration indicators and so-called universal indicators are used for acidic or basic gases, and so-called redox titration indicators are used for oxidizing or reducing gases. is used. These indicators are described, for example, in "Chemistry Handbook Basic Edition (June 20, 1975, published by Maruzen Co., Ltd.) No. 15.
26 to 1527" may be selected and used as appropriate. Preferred indicators for acidic gases or basic gases include, for example, methyl olelene, thymol blue, and phenolphthalein. , and for oxidizing gases or reducing gases, such as neutral red and diphenylamine.

The gas sorption cylinder of the present invention has two sorption layers: a sorbent layer on the inlet side (hereinafter referred to as the first sorption layer) and a sorbent layer on the outlet side (hereinafter referred to as the second sorption layer). A sensing agent layer is interposed between the agent layers.

There is no particular limit to the amount of sorbent in the first sorption layer, but in practice it is preferably an amount that allows continuous operation for at least 5 days.

The ratio of the sorbent in the first sorbent layer to that in the second sorbent layer depends on the time required from the detection agent's color change to its stop before breakthrough, the type and concentration of the specific component, and the amount of sorbent in the second sorbent layer. Although it cannot be determined unconditionally depending on the type and sorption conditions, it is usually 0.0
It is said to be 5 to 0.3 times.

In addition, the amount of the detection agent is not particularly limited, but usually the first
0.05 to 0.3 relative to the volume of sorbent in the sorption layer
It is said to be doubled. Further, the sorbents used in the first sorbent and the second sorption layer may be the same or different, but the former is preferred from an industrial standpoint.

In addition, in the present invention, breakthrough refers to a specific component in the sorption layer outlet gas.
In particular, it refers to a harmful gas reaching a certain limit, which in the case of a harmful gas is a public or private value that does not chemically and/or biologically contaminate the environment, and other components. In some cases, it is a private value determined primarily from an economic and technical standpoint.

In order to see the discoloration of the detection agent from the outside, use a transparent material for the entire sorption cylinder or the part of the sorption cylinder corresponding to the detection agent layer, or install a sight glass or the like in the part of the sorption cylinder corresponding to the detection agent layer. provided.

In the present invention, a specific component in the exhaust gas from the outlet end of the first sorption layer is detected by interposing the detection agent layer between the first sorption layer and the second sorption layer. Therefore, it is possible to accurately detect the breakthrough of the sorbent in the first sorption layer, and to easily and accurately predict the breakthrough of the sorbent in the second sorption layer. It is now possible to accurately predict the effective operating time and stop the operation of the sorption tube just before breakthrough, making it unnecessary to take a large safety factor.

The present invention will be explained in more detail with reference to the following examples.

Example 1 (1) After drying 1 kg (2.2 l) of granular activated carbon at 120°C for 2 hours, an aqueous solution of 140 g of reagent grade potassium hydroxide (purity 85%) dissolved in 800 ml of pure water was added to the dry activated carbon. Impregnated and dried again at 120°C overnight,
2.2 l of sorbent was obtained.

As the detection agent, activated alumina impregnated with phenolphthalein was used. That is, activated alumina 3
After drying 00g (0.4l) at 120℃ for 2 hours,
To this dry activated alumina, phenolphthalein 0.3
g and potassium hydroxide aqueous solution (3 g of potassium hydroxide to 1 water
The sample was impregnated with a mixed solution of 0 ml (dissolved in 0 ml) and 200 ml of methanol, and dried in vacuum under heating to obtain a detection agent.

(2) A cylindrical container was filled with a portion of each of the sorbent and detection agent obtained as in (1) to form a gas sorption cylinder.

That is, in FIG. 1, a transparent cylindrical container 1 made of polycarbonate with an inner diameter of 60 mm has a layer height of 45 mm in order from the top.
A gas storage cylinder filled with a sorbent, a detection agent, and a sorbent in order so that the thickness of each layer is 5 cm, 5 cm, and 5 cm, and each layer is a first sorption layer 2, a detection agent layer 3, and a second sorption layer 4. I made 5.

The upper end of this gas sorption cylinder 5 is connected to a silicon wafer etching bath 6 containing an etching solution consisting of hydrochloric acid, acetic acid and phosphoric acid through a pipe 7, while the lower end of the gas sorption cylinder 5 is connected to a vacuum pump 8. I communicated with them via pipe 9.

When operated under a reduced pressure of 10 mmHg, the detection agent changed color 30 days after the start of operation, so 3 days later, the operation of this gas sorption cylinder 5 was stopped and other gas sorption cylinders (see Figure 1) were replaced. (not shown). Immediately before this stop, the exhaust gas from the vacuum pump 8 was analyzed, and no acidic gas was detected, and as a matter of course, no abnormality was observed in the vacuum pump 8. Moreover, almost all of the sorbent in the second sorption layer lost its sorption capacity and was on the verge of breakthrough.

Comparative Example 1 The same procedure as Example 1 was carried out except that the second sorption layer was omitted.

As in Example 1, the detection agent changed color on the 30th day after the start of operation, and the next day, an abnormality was observed in the vacuum pump, so the operation was stopped. Upon inspecting the inside of the pump, a large amount of rust was discovered due to corrosion caused by acid.

Example 2 (1) 98% sulfuric acid 114 instead of potassium hydroxide aqueous solution
A sorbent was obtained in the same manner as in Example (1) except that 800 ml of a pure aqueous solution of g was used.

A detection agent was also obtained in the same manner as in Example 1 (1), except that instead of the phenolphthalein solution, a solution prepared by dissolving 0.1 g of methyl orange and 1 g of sulfuric acid in 200 ml of water was used.

(2) A gas sorption tube was prepared by filling a transparent cylindrical container with the sorbent and detection agent obtained in (1) in the same manner as in Example 1 (2).

A gas mixture of ammonia and nitrogen having an ammonia concentration of 0.2 vol% was flowed into this gas sorption cylinder at a rate of 10 l/min. The detection agent changed color in 8 days, so we immediately monitored the ammonia concentration in the outlet gas using a Kitagawa detection tube, and found that it was substantially detected, or that ammonia was still substantially detected even after 16 hours had passed. However, it was 0.1 vol% after 20 hours.

Example 3 (1) Instead of potassium hydroxide aqueous solution, ferrous sulfate 28
Example 1 (1
) A sorbent was obtained in the same manner.

Also, instead of the phenolphthalein solution, 1.5 g of 1,10-phenanthroline and 0.0 g of ferrous sulfate (heptahydrate) were used.
A detecting agent was obtained in the same manner as in Example 1 (1) except that a solution in which 7 g was dissolved in 200 ml of water was used.

(2) A gas sorption cylinder was prepared by filling a transparent cylindrical container with the sorbent and detection agent obtained in (1) in the same manner as in Example 1 (2).

A gas mixture of chlorine and nitrogen containing a chlorine concentration of 20 ppm was flowed through this gas sorption cylinder at a rate of 16 l/mjn. The detection agent is 9
The color changed after a few days, so we immediately monitored the chlorine concentration in the outlet gas using a Kitagawa gas detector tube, and found that it was virtually undetectable. After discoloration, chlorine was substantially undetectable even after 16 hours had passed, and chlorine was 10 ppm after 20 hours.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet of a gas sorption device incorporating the gas sorption cylinder of the present invention. Sorption tube 6 Silicon wafer etching layer and 8 Vacuum pump Patent applicant Itsube Suhara Representative of Nippon Bionics Co., Ltd.

Claims (1)

[Claims] In a gas sorption cylinder filled with a sorbent for adsorption and removal of specific components in a gas mixture and a detection agent for detecting breakthrough, a detection agent layer is interposed between the two sorbent layers. A gas sorption cylinder characterized by